Help with samsung psu hpt-4254 plasma

[HardCoreDore]

I have the standard clicking on an off issue with this plasma. Initially it started cycling on and off, but would eventually start and play the melody. After a few weeks of this it will not turn on at all. It doesn't really try to start but just clicks. No melody is played either.

Upon inpection of the PSU, I noticed that a few of teh caps were swollen. They weren't yet leaking but had bulging tops. I purchased a repair kit off ebay to replace these caps. Still no luck unfortunately.

I have a DMM and would like to know if anyone can walk me through testing the power supply and various components to see what else needs to be fixed?

Any help would be appreciated.

[budm]

Re: Help with samsung psu hpt-4254 plasma

You can start with this:
https://www.badcaps.net/forum/showthread.php?t=39740

[tw2005]

Re: Help with samsung psu hpt-4254 plasma

If the FETs have not blown, could be as simple as cracked solder joints on the Heatsinked FETS, especially the centre heatsink.

If that's the case i'd reflow them all.

Hope I've got the correct locations
QS801,QS802, QX801 and QX802

you'll have to confirm if that's the correct PSU, also BN44-00159A fitted to this model. Picture is of 50" but same PSu with downgraded FETs

[freakaftr8]

Re: Help with samsung psu hpt-4254 plasma

i f I recall this particular model was plagued with poor solder connections on the power supply. Check connections on all transformers and MOSFET transistors
You might need a magnifying glass but I guarantee you're going to find some

[Shinju]

Re: Help with samsung psu hpt-4254 plasma

^ this

Check all the fets on the aluminum rails as well as then soldier points for them too.


Check this video out.

http://m.youtube.com/watch?v=za3EixgxBkk

[nomoresonys]

Re: Help with samsung psu hpt-4254 plasma

I have the standard clicking on an off issue with this plasma. Initially it started cycling on and off, but would eventually start and play the melody. After a few weeks of this it will not turn on at all. It doesn't really try to start but just clicks. No melody is played either.

Upon inpection of the PSU, I noticed that a few of teh caps were swollen. They weren't yet leaking but had bulging tops. I purchased a repair kit off ebay to replace these caps. Still no luck unfortunately.

I have a DMM and would like to know if anyone can walk me through testing the power supply and various components to see what else needs to be fixed?

Any help would be appreciated.

might get your testing details here http://elektrotanya.com/?q=showresul...oria=&kat2=all

[HardCoreDore]

Re: Help with samsung psu hpt-4254 plasma

^ this

Check all the fets on the aluminum rails as well as then soldier points for them too.


Check this video out.

http://m.youtube.com/watch?v=za3EixgxBkk

I've watched that video about 10 times before. I did reflow the solder on the smaller mosfets when I was replacing the swollen caps. How do I go about testing the mosfets with a DMM? I am basically illiterate when it comes to this stuff so please be specific as to DMM setting, and where to place the electrodes.

thanks

[Shinju]

Re: Help with samsung psu hpt-4254 plasma

I was referring to bad solider connections on the fets. Shopjimmy sells a repair kit for this power supply.

[HardCoreDore]

Re: Help with samsung psu hpt-4254 plasma

But is there any way to test these components before buying more parts? I already spent $15 on a capacitor repair kit to no avail. I need to know how to properly test continuity on these parts.

[tw2005]

Re: Help with samsung psu hpt-4254 plasma

I've watched that video about 10 times before. I did reflow the solder on the smaller mosfets when I was replacing the swollen caps. How do I go about testing the mosfets with a DMM? I am basically illiterate when it comes to this stuff so please be specific as to DMM setting, and where to place the electrodes.

thanks

what about all the ones I've marked? If failed they go short normally, so set meter to buzzer or continuity / diode and probe across each combination of 2 legs of the FETs. the ones i listed are for Va and Vs voltages and are the ones that blow

[Agent24]

Re: Help with samsung psu hpt-4254 plasma

Upon inpection of the PSU, I noticed that a few of teh caps were swollen. They weren't yet leaking but had bulging tops. I purchased a repair kit off ebay to replace these caps. Still no luck unfortunately.

That's a red flag to me. eBay sellers often sell rubbish\fake capacitors. Who did you buy them from, what brand are they, what do they look like?

[HardCoreDore]

Re: Help with samsung psu hpt-4254 plasma

I can post pictures of them, but they look legit to me. 2 are Panasonic and one is a Nichion.

I'll try to check those fets in the morning. There are 3 leads obviously. Do I test continuity on the outer leads?

[tw2005]

Re: Help with samsung psu hpt-4254 plasma

I can post pictures of them, but they look legit to me. 2 are Panasonic and one is a Nichion.

I'll try to check those fets in the morning. There are 3 leads obviously. Do I test continuity on the outer leads?

often they'll short fully, just do 1-2, 1-3, 2-3

If they have shorted there's a lot of small smd stuff underside that fails with them too usually.
I've got one (50") that both the Va tract and Vs blew and it continually clicked. bit of a mess really as that and the ymain and upper buffer blew all at once.

[HardCoreDore]

Re: Help with samsung psu hpt-4254 plasma

I haven't had a chance to check the fets yet, but I must say why are these TV's so crappy and why is a good company like Samsung not standing behind them? (I am aware of a cap recall on a few select TV's but mine is not one of those recalled.)

The previous 2 (tube style) T.V.'s I had prior to this are still working. One is over 20 years old and was used every day for about 15 years. The other is about 10 years old and although it hasn't been used much, it still looks as good as the day it was bought.

Is this our future? Having to buy new worthless crap every 3-5 years? Sorry, but I just needed to vent. Everything electronic that I own has decided to crap out in the last year. It just doesn't stop...

[tw2005]

Re: Help with samsung psu hpt-4254 plasma

I haven't had a chance to check the fets yet, but I must say why are these TV's so crappy and why is a good company like Samsung not standing behind them? (I am aware of a cap recall on a few select TV's but mine is not one of those recalled.)

The previous 2 (tube style) T.V.'s I had prior to this are still working. One is over 20 years old and was used every day for about 15 years. The other is about 10 years old and although it hasn't been used much, it still looks as good as the day it was bought.

Is this our future? Having to buy new worthless crap every 3-5 years? Sorry, but I just needed to vent. Everything electronic that I own has decided to crap out in the last year. It just doesn't stop...

Get use to it. That tv is about 7yo if you check out the specs for caps lifespan etc plus heat and leadfree solder which tends to be brittle its done well.different technology . I do believe they design these for shorter lifespans reduced production costs.lots of the 2011/12 panasonics have quality issues .for those of us that can repair component level we can make them last a bit longer as boards disappear

[Shinju]

Re: Help with samsung psu hpt-4254 plasma

To give credit to Samsung, these HP line of plasma panels are pretty well built, outside of the power supply.

[freakaftr8]

Re: Help with samsung psu hpt-4254 plasma

You think that's crappy? these new super flat flat screen probably not even going to last five years. Seems like everything these days either have a non repairable issue like a panel problem or something else to that nature. They keep getting smaller and smaller and the cooling efficiency keeps getting less and less especially around the bezels and the frames where the IC's need active cooling against the metal frame. All these things keep getting center that active cooling efficiency reduces. just my two cents worth

[HardCoreDore]

Re: Help with samsung psu hpt-4254 plasma

I tried testing the mosfets earlier with mixed results. I couldn't figure out the multimeter I borrowed from a friend. I think the leads are bad on it.

I'm getting a fluke from another friend and I'll report back. I did check the welds for cold solder joints and any that looked suspect I reflowed. Still not working though.